/*
 **********************************************************************
 ** md5.c                                                            **
 ** RSA Data Security, Inc. MD5 Message Digest Algorithm             **
 ** Created: 2/17/90 RLR                                             **
 ** Revised: 1/91 SRD,AJ,BSK,JT Reference C Version                  **
 **********************************************************************
 */

/*
 **********************************************************************
 ** Copyright (C) 1990, RSA Data Security, Inc. All rights reserved. **
 **                                                                  **
 ** License to copy and use this software is granted provided that   **
 ** it is identified as the "RSA Data Security, Inc. MD5 Message     **
 ** Digest Algorithm" in all material mentioning or referencing this **
 ** software or this function.                                       **
 **                                                                  **
 ** License is also granted to make and use derivative works         **
 ** provided that such works are identified as "derived from the RSA **
 ** Data Security, Inc. MD5 Message Digest Algorithm" in all         **
 ** material mentioning or referencing the derived work.             **
 **                                                                  **
 ** RSA Data Security, Inc. makes no representations concerning      **
 ** either the merchantability of this software or the suitability   **
 ** of this software for any particular purpose.  It is provided "as **
 ** is" without express or implied warranty of any kind.             **
 **                                                                  **
 ** These notices must be retained in any copies of any part of this **
 ** documentation and/or software.                                   **
 **********************************************************************
 */

#include "md5.h"

/* forward declaration */
void Transform (
                 UINT4 *buf,
                 UINT4 *in
                 );

static unsigned char PADDING[64] = {
                                    0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                                    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                                    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                                    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                                    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                                    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                                    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                                    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};

/* F, G and H are basic MD5 functions: selection, majority, parity */
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z))) 

/* ROTATE_LEFT rotates x left n bits */
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

/* FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4 */
/* Rotation is separate from addition to prevent recomputation */
#define FF(a, b, c, d, x, s, ac) \
  {(a) += F ((b), (c), (d)) + (x) + (UINT4)(ac); \
   (a) = ROTATE_LEFT ((a), (s)); \
   (a) += (b); \
  }
#define GG(a, b, c, d, x, s, ac) \
  {(a) += G ((b), (c), (d)) + (x) + (UINT4)(ac); \
   (a) = ROTATE_LEFT ((a), (s)); \
   (a) += (b); \
  }
#define HH(a, b, c, d, x, s, ac) \
  {(a) += H ((b), (c), (d)) + (x) + (UINT4)(ac); \
   (a) = ROTATE_LEFT ((a), (s)); \
   (a) += (b); \
  }
#define II(a, b, c, d, x, s, ac) \
  {(a) += I ((b), (c), (d)) + (x) + (UINT4)(ac); \
   (a) = ROTATE_LEFT ((a), (s)); \
   (a) += (b); \
  }

void MD5Init ( MD5_CTX *mdContext )
{
    mdContext->i[0] = mdContext->i[1] = ( UINT4 ) 0;

    /* Load magic initialization constants.
     */
    mdContext->buf[0] = ( UINT4 ) 0x67452301;
    mdContext->buf[1] = ( UINT4 ) 0xefcdab89;
    mdContext->buf[2] = ( UINT4 ) 0x98badcfe;
    mdContext->buf[3] = ( UINT4 ) 0x10325476;
}

void MD5Update (
                 MD5_CTX *mdContext,
                 const unsigned char *inBuf,
                 unsigned int inLen
                 )
{
    UINT4 in[16];
    int mdi;
    unsigned int i, ii;

    /* compute number of bytes mod 64 */
    mdi = ( int ) ( ( mdContext->i[0] >> 3 ) & 0x3F );

    /* update number of bits */
    if ( ( mdContext->i[0] + ( ( UINT4 ) inLen << 3 ) ) < mdContext->i[0] )
        mdContext->i[1] ++;
    mdContext->i[0] += ( ( UINT4 ) inLen << 3 );
    mdContext->i[1] += ( ( UINT4 ) inLen >> 29 );

    while ( inLen -- )
    {
        /* add new character to buffer, increment mdi */
        mdContext->in[mdi ++] = * inBuf ++;

        /* transform if necessary */
        if ( mdi == 0x40 )
        {
            for ( i = 0, ii = 0; i < 16; i ++, ii += 4 )
                in[i] = ( ( ( UINT4 ) mdContext->in[ii + 3] ) << 24 ) |
                ( ( ( UINT4 ) mdContext->in[ii + 2] ) << 16 ) |
                ( ( ( UINT4 ) mdContext->in[ii + 1] ) << 8 ) |
                ( ( UINT4 ) mdContext->in[ii] );
            Transform (mdContext->buf, in);
            mdi = 0;
        }
    }
}

void MD5Final (
                MD5_CTX *mdContext,
                unsigned char * digest
                )
{
    UINT4 in[16];
    int mdi;
    unsigned int i, ii;
    unsigned int padLen;

    /* save number of bits */
    in[14] = mdContext->i[0];
    in[15] = mdContext->i[1];

    /* compute number of bytes mod 64 */
    mdi = ( int ) ( ( mdContext->i[0] >> 3 ) & 0x3F );

    /* pad out to 56 mod 64 */
    padLen = ( mdi < 56 ) ? ( 56 - mdi ) : ( 120 - mdi );
    MD5Update (mdContext, PADDING, padLen);

    /* append length in bits and transform */
    for ( i = 0, ii = 0; i < 14; i ++, ii += 4 )
        in[i] = ( ( ( UINT4 ) mdContext->in[ii + 3] ) << 24 ) |
        ( ( ( UINT4 ) mdContext->in[ii + 2] ) << 16 ) |
        ( ( ( UINT4 ) mdContext->in[ii + 1] ) << 8 ) |
        ( ( UINT4 ) mdContext->in[ii] );
    Transform (mdContext->buf, in);

    /* store buffer in digest */
    for ( i = 0, ii = 0; i < 4; i ++, ii += 4 )
    {
        digest[ii] = ( unsigned char ) ( mdContext->buf[i] & 0xFF );
        digest[ii + 1] =
            ( unsigned char ) ( ( mdContext->buf[i] >> 8 ) & 0xFF );
        digest[ii + 2] =
            ( unsigned char ) ( ( mdContext->buf[i] >> 16 ) & 0xFF );
        digest[ii + 3] =
            ( unsigned char ) ( ( mdContext->buf[i] >> 24 ) & 0xFF );
    }
}

/* Basic MD5 step. Transform buf based on in.
 */
void Transform (
                 UINT4 *buf,
                 UINT4 *in
                 )
{
    UINT4 a = buf[0], b = buf[1], c = buf[2], d = buf[3];

    /* Round 1 */
#define S11 7
#define S12 12
#define S13 17
#define S14 22
    FF (a, b, c, d, in[ 0], S11, 3614090360); /* 1 */
    FF (d, a, b, c, in[ 1], S12, 3905402710); /* 2 */
    FF (c, d, a, b, in[ 2], S13, 606105819); /* 3 */
    FF (b, c, d, a, in[ 3], S14, 3250441966); /* 4 */
    FF (a, b, c, d, in[ 4], S11, 4118548399); /* 5 */
    FF (d, a, b, c, in[ 5], S12, 1200080426); /* 6 */
    FF (c, d, a, b, in[ 6], S13, 2821735955); /* 7 */
    FF (b, c, d, a, in[ 7], S14, 4249261313); /* 8 */
    FF (a, b, c, d, in[ 8], S11, 1770035416); /* 9 */
    FF (d, a, b, c, in[ 9], S12, 2336552879); /* 10 */
    FF (c, d, a, b, in[10], S13, 4294925233); /* 11 */
    FF (b, c, d, a, in[11], S14, 2304563134); /* 12 */
    FF (a, b, c, d, in[12], S11, 1804603682); /* 13 */
    FF (d, a, b, c, in[13], S12, 4254626195); /* 14 */
    FF (c, d, a, b, in[14], S13, 2792965006); /* 15 */
    FF (b, c, d, a, in[15], S14, 1236535329); /* 16 */

    /* Round 2 */
#define S21 5
#define S22 9
#define S23 14
#define S24 20
    GG (a, b, c, d, in[ 1], S21, 4129170786); /* 17 */
    GG (d, a, b, c, in[ 6], S22, 3225465664); /* 18 */
    GG (c, d, a, b, in[11], S23, 643717713); /* 19 */
    GG (b, c, d, a, in[ 0], S24, 3921069994); /* 20 */
    GG (a, b, c, d, in[ 5], S21, 3593408605); /* 21 */
    GG (d, a, b, c, in[10], S22, 38016083); /* 22 */
    GG (c, d, a, b, in[15], S23, 3634488961); /* 23 */
    GG (b, c, d, a, in[ 4], S24, 3889429448); /* 24 */
    GG (a, b, c, d, in[ 9], S21, 568446438); /* 25 */
    GG (d, a, b, c, in[14], S22, 3275163606); /* 26 */
    GG (c, d, a, b, in[ 3], S23, 4107603335); /* 27 */
    GG (b, c, d, a, in[ 8], S24, 1163531501); /* 28 */
    GG (a, b, c, d, in[13], S21, 2850285829); /* 29 */
    GG (d, a, b, c, in[ 2], S22, 4243563512); /* 30 */
    GG (c, d, a, b, in[ 7], S23, 1735328473); /* 31 */
    GG (b, c, d, a, in[12], S24, 2368359562); /* 32 */

    /* Round 3 */
#define S31 4
#define S32 11
#define S33 16
#define S34 23
    HH (a, b, c, d, in[ 5], S31, 4294588738); /* 33 */
    HH (d, a, b, c, in[ 8], S32, 2272392833); /* 34 */
    HH (c, d, a, b, in[11], S33, 1839030562); /* 35 */
    HH (b, c, d, a, in[14], S34, 4259657740); /* 36 */
    HH (a, b, c, d, in[ 1], S31, 2763975236); /* 37 */
    HH (d, a, b, c, in[ 4], S32, 1272893353); /* 38 */
    HH (c, d, a, b, in[ 7], S33, 4139469664); /* 39 */
    HH (b, c, d, a, in[10], S34, 3200236656); /* 40 */
    HH (a, b, c, d, in[13], S31, 681279174); /* 41 */
    HH (d, a, b, c, in[ 0], S32, 3936430074); /* 42 */
    HH (c, d, a, b, in[ 3], S33, 3572445317); /* 43 */
    HH (b, c, d, a, in[ 6], S34, 76029189); /* 44 */
    HH (a, b, c, d, in[ 9], S31, 3654602809); /* 45 */
    HH (d, a, b, c, in[12], S32, 3873151461); /* 46 */
    HH (c, d, a, b, in[15], S33, 530742520); /* 47 */
    HH (b, c, d, a, in[ 2], S34, 3299628645); /* 48 */

    /* Round 4 */
#define S41 6
#define S42 10
#define S43 15
#define S44 21
    II (a, b, c, d, in[ 0], S41, 4096336452); /* 49 */
    II (d, a, b, c, in[ 7], S42, 1126891415); /* 50 */
    II (c, d, a, b, in[14], S43, 2878612391); /* 51 */
    II (b, c, d, a, in[ 5], S44, 4237533241); /* 52 */
    II (a, b, c, d, in[12], S41, 1700485571); /* 53 */
    II (d, a, b, c, in[ 3], S42, 2399980690); /* 54 */
    II (c, d, a, b, in[10], S43, 4293915773); /* 55 */
    II (b, c, d, a, in[ 1], S44, 2240044497); /* 56 */
    II (a, b, c, d, in[ 8], S41, 1873313359); /* 57 */
    II (d, a, b, c, in[15], S42, 4264355552); /* 58 */
    II (c, d, a, b, in[ 6], S43, 2734768916); /* 59 */
    II (b, c, d, a, in[13], S44, 1309151649); /* 60 */
    II (a, b, c, d, in[ 4], S41, 4149444226); /* 61 */
    II (d, a, b, c, in[11], S42, 3174756917); /* 62 */
    II (c, d, a, b, in[ 2], S43, 718787259); /* 63 */
    II (b, c, d, a, in[ 9], S44, 3951481745); /* 64 */

    buf[0] += a;
    buf[1] += b;
    buf[2] += c;
    buf[3] += d;
}
